title: IgG4-related lung disease showing high standardized uptake values on FDG-PET: report of two cases.
abstract: Immunoglobulin G4 (IgG4)-related lung disease is a disease in which IgG4-positive plasma cells and lymphocytes infiltrate lung tissues along with immunohistochemically evident fibrous interstitial proliferation in the background, in addition to hyper-IgG4 disease. The diagnosis of this disease can be difficult. Here, we report 2 cases with IgG4-related lung disease that was difficult to differentiate from malignant tumors because both cases had pulmonary lesions showing high standardized uptake values (SUV) on positron emission tomography (PET). Case 1: A 75-year-old man under treatment for autoimmune pancreatitis and diabetes mellitus was noted to have multiple nodular opacities in both lungs and a mass density in the right paravertebral region on computed tomography (CT). As high SUVmax was noted for both lesions on exploration by fluorodeoxyglucose (FDG)-PET/CT, an advanced malignant tumor was diagnosed and a video-assisted thoracoscopic (VATS) biopsy was performed and diagnosed IgG4-related lung disease. Case 2: A 48-year-old woman consulted our clinic with a chief complaint of bloody sputum. Chest CT revealed a mass density with 12-, 13-, and 16-mm spiculations in the S2 segment of the right upper lobe and irregular thickening of the pleura including the paravertebral region. The lesion was a mass showing high SUV in the S2 segment on FDG-PET. Malignancy was suspected from the imaging findings, and a VATS biopsy was performed and diagnosed IgG4-related lung disease. Actively undertaking VATS biopsy in cases with this disease is valuable for making the differential diagnosis between malignant tumors and IgG4-related lung disease, since the diagnosis can be difficult in some patients showing high SUV.
authors.affiliation: Department of Respiratory Center, Asahikawa Medical University, Midorigaoka-Higashi 2-1-1-1, Asahikawa, Hokkaido 078-8510, Japan. k1111@asahikawa-med.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kitada
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Matuda
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hayashi
authors.forename: Kei
authors.initials: K
authors.lastname: Ishibashi
authors.forename: Kensuke
authors.initials: K
authors.lastname: Oikawa
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Miyokawa
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Ohsaki
mesh_terms: D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D008171:Lung Diseases / Q000000981:diagnostic imaging* / Q000276:immunology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D020775:Thoracic Surgery, Video-Assisted; D014057:Tomography, X-Ray Computed
chemical_list: D007074:Immunoglobulin G; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18